There are some threads in which the community is discussing the topic “multiplayer”. You might find one or the other information / suggestion / idea there… not so much officially confirmed yet.
I cannot think of a way the coop multiplayer would work if you can only control what player A controls also. What I was thinking on how it could work would be similar to maybe DF + DayZ.
You would start in an area with your settlers in a random location on the map or you can choose to start off next to your friends. Your friends cannot control your own settlers unless you give them “permission.” The settlers could also help other settlers that are allied with you to build certain structures but…
I’ve searched on Discourse about how Multiplayer would be hosted… but I haven’t found any specific topics on this topic. If there is, then @SteveAdamo and @Geoffers747 , feel free to merge.